This invention pertains generally to weighing instruments and more particularly to a counting scale for determining the number of articles in a group from the weight of the articles.
Heretofore, digital counting scales have been provided for determining the number of articles in a group by first weighing a known quantity or sample of articles to determine the unit weight, then weighing the group and dividing the group weight by the unit weight to determine the count. Systems utilized in the past for this purpose have generally been one of two types: systems utilizing a single scale for both weighings and systems utilizing a low capacity scale for weighing the sample and a high capacity scale for weighing the unknown quantity.
Both types of systems are subject to certain problems and disadvantages. The single scale systems are generally limited to a relatively small number of articles since they do not have both the resolution required to accurately weigh a small sample and the range or capacity required to weigh a large load. Dual scale systems generally have a greater range, but the two scales can be awkward to use and difficult to calibrate with sufficient accuracy to provide satisfactory results. Proper calibration is particularly difficult with electronic scales utilizing load cells and amplifiers which generally exhibit some non-linearities in practice.